Abstract

Rice Hulls (RH) are the annually renewable wastes from processing of rice hulls. They are often dumped, and toxic gaseous substances are emitted while the rice hulls decompose. That creates considerable environmental problems. Over 50 thousand tons of rice hulls are annually produced in Kazakhstan. The world volume of the rice hulls generation amounts to 150-180 million tons per year. To address this environmental challenge, the following novel intellectual property methodologies have been proposed for processing wase rice hulls thereby producing new materials such as the solid product silica-carbon. It is a nanocomposite produced by nanoparticles of carbon and silicon dioxide, which were present in the amorphous form and has proven to be advanced filler, sorbent, and fodder supplement for the farm poultry. In addition, this product can be used for producing crystal whiskers B-SiC and polycrystalline silicon. The organic product (aqueous solution of carboxylic acids, phenols, ketones, cyclic aliphatic hydrocarbons, and spirits) is a high-selective collector, plant growth stimulant and an antiseptic agent. During development, it was found that in the temperature range of 300-500 °С three hydrocarbon phases were present in silica-carbon: the stable phase, unstable polynaphthenic phase and resinous phase. At temperatures of 600-700 °С the polynaphthenic phase partially transformed into the carbon phase and resinous hydrocarbons volatilized. Hence, technology was developed to produce silica-carbon with the stable-composition hydrocarbons that met the requirements as to the fillers for hydrocarbon structural materials and elastomers as well as the charge material for production of high-purity silicon.
In summary, silica-carbon is a polyfunctional material and can be used as a filler of elastomers and carbon structural materials, and as a louder additive in poultry farming. Considering the great demand for Kazakhstan and the world in for this material, its production is timely.

Keywords:Rice hulls; Filler for elastomers; Fodder supplement; Sorbent; Stimulant; Antiseptic